INCORPORATION BY REFERENCE: Applicant(s) hereby incorporate herein by reference, any and all U.S. patents, U.S. patent applications, and other documents and printed matter cited or referred to in this application.
1. Field of the Invention
This invention relates generally to packing knives and box cutters and more particularly to a hand-held knife with retractable blade and shelf sharpening feature.
2. Description of Related Art
The following art defines the present state of this field:
Wright, U.S. Pat. No. 1,465,751 describes a knife comprising a hollow sheath, a blade holder slidably mounted in the sheath and provided with a slot at the front end, a blade having, one end thereof mounted in the slot, and a clamp over the front end and adapted to clamp the blade into operative position and to release the same for removal thereof.
Blow, U.S. Pat. No. 1,507,043 describes a pocket knife, a casing, at least one blade slidably mounted therein, sharpening means arranged at the end of the casing to operate on the cutting edge of the blade spring means to hold the cutting edge of the blade in engagement with the sharpening means and a locking device for securing the blade in the open or closed position.
Frank et al., U.S. Pat. No. 1,890,506 describes an elongated, hollow handle having an elongated slot formed through one side near one end, a leaf spring mounted over the slot and having one end fastened to the handle at the inner end of the slot, the forward end of the sping being free, a sharpening element mounted at the inner side of the free end of the spring, a knife blade and connected blade rod reciprocatingly mounted through the handle, the blade being at the same end with the sharpening element and the edge of the blade being turned towards the element, the blade being beveled at its juncture with the said blade rod so as to enable the sharpening element to clamp and ride upon the edge of the blade as it is drawn backward.
Frank, U.S. Pat. No. 2,337,158 describes an elongated, frame-like handle, formed open through its medial portion and having aligned slots formed longitudinally through its ends, a thin cutting blade and a connected thin blade rod pass slidably through the handle and through the end slots therethrough, and a means on the handle for sharpening the knife as it is reciprocated.
Yarrow, U.S. Pat. No. 2,291,128 describes a knife assembly comprising a blade having a lengthwise guide way, a shaft for the blade removably attachable to a handle, which provides pivotal engaging means at its inner end, said engaging means cooperating with said guide way to, at times, direct the blade""s edge against a sharpening means, which is supported by the handle, and a means for detachably fastening the free end of the handle to the haft.
Winyard et al., U.S. Pat. No. 4,862,590 describes a retractable blade knife having a self-sharpening facility, which can be selectively rendered inoperable. The sharpener is spring biased in an upward direction so as to be urged into engagement with the cutting edge of a knife blade. A manually operable release means is provided to permit the sharpener to be held in an inoperable position. An assembly of which the sharpener forms a part also functions as a stop means which positively prevents movement of the knife blade into its extended position. Such extension is possible only upon operation of the release means, but that is only necessary during initial outward movement of the knife blade. The sharpener is arranged to sharpen the cutting edge of the blade up to the tip of the blade. Positive locking means is provided to prevent inward movement of the blade when working under load in the extended position.
Steinman et al, U.S. Pat. No. 5,519,908 describes a combination tool having a knife blade, a rasping blade and a knife blade sharpener combined into a single handle member. Preferably, the knife blade is extendable and retractable from and into the handle member, respectively. In the preferred embodiment, the knife blade sharpener is biased upward against the knife blade but fixed longitudinally. Accordingly, the knife blade sharpener abrasively contacts the knife blade thereby removing debris from the knife blades and maintaining the knife blade in a sharpened configuration. The rasping blade is preferably positioned in a rasping blade housing secured to the handle member opposite the knife blade and the knife blade sharpener; In operation, the user is not required to alter his or her grip when changing from cutting to rasping but merely moves the handle member forward to bring the rasping blade into contact with the material to be rasped.
Gringer et al., U.S. Pat. No. 6,487,778 describes an improved automatically retractable cutting device including a housing having a guide slot, with one or more notches disposed in the guide slot, a return spring within the housing, and a blade carrier disposed within the housing and biased by the return spring. The blade carrier includes a thumb piece extending through the guide slot, the thumb piece having a protuberance adapted to at least partially frictionally engage the notch during movement of the thumb piece along the guide slot to enable the thumb piece to be held in position adjacent to the notch with reduced force. Each notch may include a forward direction ramping surface, whereby reduced force is required to prevent further blade extension, and/or a reverse direction ramping surface, whereby reduced force is required to prevent blade retraction. Each ramping surface is preferably angled at less than ninety degrees. The housing may be formed by attachable halves, each of which includes notches, whereby the notches are substantially symmetrically aligned when the housing is assembled.
McPherson""s Limited, EP 0271223 describes a retractable blade knife having a self-sharpening facility, which can be selectively rendered inoperable. The sharpener is spring biased in an upward direction so as to be urged into engagement with the cutting edge of a knife blade, and manually operable release means is provided to permit the sharpener to be held in an inoperable position. An assembly of which the sharpener forms part also functions as stop means which positively prevents movement of the knife blade into its extended position. Such extension is possible only upon operation of the release means, but that is only necessary during initial outward movement of the knife blade. The sharpener is arranged to sharpen the cutting edge of the blade up to the tip of the blade. Positive locking means is provided to prevent inward movement of the blade when working under load in the extended position.
The prior art teaches a utility knife with pressure reducing slot, several versions of knifes with retractable blades, a knife with built-in sharpener, a cutting and rasping combination tool, a retractable pocket knife, and a knife with a pivotal sharpening assembly, but does not teach a retracting blade knife enabled for blade extension-retraction with and without sharpening action depending upon downward finger pressure on an actuation lever. The present invention fulfills this need and provides further related advantages as described in the following summary.
The present invention teaches certain benefits in construction and use which give rise to the objectives described below.
A cutter has a blade housing; a blade carrier; and a blade engaged within the blade carrier. The blade housing receives the blade carrier and blade in sliding engagement along a longitudinal direction for retracting the blade into the housing and for extending the blade forward of the blade housing. The blade carrier is further movable between an upwardly biased position and a downwardly depressed position within the blade housing against a spring biasing element which urges the blade carrier to the upwardly biased position for locking the blade carrier in one of a plurality of slots for fixing the blade at a selected degree of extension. The blade carrier may be partially depressed to disengage the blade carrier from the slots enabling longitudinal motion for blade extension-retraction, and may be fully depressed to engage a cutting edge of the blade with a sharpening stone for honing the blade as the blade carrier moves. The prior art does not teach a tool with this dual depression action so that sharpening the blade only takes place when necessary and when desired, yet the same finger action is used to drive the blade during normal use. The prior art also does not teach the use of three sharpening surfaces so that the blade may be sharpened over the full length of the blade including the blade tip.
A primary objective of the present invention is to provide an apparatus and method of use of such apparatus that provides advantages not taught by the prior art.
Another objective is to provide such an invention capable of extending and retracting a knife blade with simple finger manipulation.
A further objective is to provide such an invention capable of engaging and disengaging the knife""s blade edge by finger pressure alone.
A still further objective is to provide such an invention capable of sharpening a knife blade during normal retraction of the blade.